Lubricants containing load-carrying additives



United States Patent M 3,280,028 LUBRICANTS CONTAINING LOAD-CARRYINGADDITIVES Howard J. Matson, Harvey, 11]., assignor to Sinclair Research,Inc., Wilmington, Del., a corporation of Delaware No Drawing. Filed Jan.28, 1963, Ser. No. 254,422 9 Claims. (Cl. 252-46.6)

This invention relates to a method of producing lubricating oils havinga markedly increased Timken safe load value.

Among the extreme pressure tests that lubricating oil blends aregenerally required to meet is the regular Timken break-down test. Manygear oil consumers, for instance, specify a high T imken load, usually a50-pound minimum safe load. Now, although there are many excellentextreme pressure agents that provide highly satisfactory results withregard to other extreme pressure tests such as the Shell-4 Ball Wear,Falex and SAE tests, it is not uncommon in many cases to find that theyfail to meet the Timken safe load specifications.

It has now been found that the Timken safe load value of lubricatingoils containing small effective amounts of each of an oil-solublesulfurized fatty oil and an oilsoluble phosphorus sulfide-hydrocarbonreaction product can be markedly improved by heating the additivecombination at a temperature between about 200" and 350 F., preferablyabout 225 to 275 F. The heating can be of the additive combination perse after which it is incorporated into the lubricating oil base, or itcan be of the additive combination in a mineral oil as, for instance,the lubricating oil base, which base may be present in amounts up tothose reducing the concentration of the additive combination to thatdesired in the final lubricating oil composition. It is preferred,however, to heat the additive combination separately, that is, prior toits addition to the lubricating oil base since a more rapid increase inthe Timken load value at lower temperatures is found than is obtainedfrom heating a mixture or blend of the additives and base oil and inmany instances the preferred procedure results in a higher Timken loadvalue.

The heating step of the present invention is continued for a timesuifi-cient to increase the ability of a given amount of the additive toincrease the Timken safe load value of the final lubricating oilcomposition significantly, for example, at least about 15 pounds. Theheating periods may vary with the heating temperature selected, a morerapid increase in Timken load value generally being obtained with thehigher temperatures, and generally the time will be for at least about0.5 hour up to 10 hours or more under preferred temperatures. Longerheating times may be necessary when lower temperatures within theprescribed range are employed. When heating an admixture of the additivecombination and the base oil, temperatures are selected so that aheating period of not much more than about 2 hours is employed. Heatingfor longer periods of time is generally uneconomical on a commercialscale. On the other hand, when the additives are heated separately thetime period can be longer than about 2 hours, for example, up to 10hours, preferably about 2 to 5 hours and still stay within economicallimits.

The phosphorus sulfide-hydrocarbon materials of the present invention,are the reaction products of a sulfide of phosphorus with a suitablehydrocarbon material of lubricating viscosity such as a material ofnatural petroleum 3,280,028 Patented Oct. 18, 1966 origin, for example,a heavy hydrocarbon oil of lubricating viscosity having a molecularweight above about 500, i.e. residual lubricating oils, or a synthetichydrocarbon material such as an olefin or olefin polymer having amolecular weight of from about 400 to 2000 or more. The sulfide ofphosphoruswhich may be employed with the hydrocarbon material ispreferably phosphorus pentasulfide, P 8 although P 8 P 8 or otherphosphorus sulfides or mixtures thereof can be used. Ordinarily, thephosphorus sulfide-hydrocarbon reaction is carried out at a temperatureof from about 200 to 500 F., preferably about 400 to 500 F., and in anon-oxidizing atmosphere, such at an atmosphere of nitrogen. The amountof phosphorus sulfide which can be used may range from 1 percent to 50weight percent and is preferably from about 5 percent to 25 percent ofthe hydrocarbon material. The final reaction product will usuallycontain from about 1 to 6% by weight of organically combinedphosphor-us.

In a preferred embodiment, a hydrocarbon material such as a mineral oilbright stock or cylinder stock having a viscosity within a range ofabout to 300 SUS at 210 F. is reacted with 7 to 17 weight percent ofphosphorus pentasulfide at a temperature between about 400 to 500 F. fora period of about 10 to 20 hours. By reacting a phosphorus sulfide witha bright stock, for example, the formation of oil-insoluble productswhich are prosludging in typical lubricating oil blends are greatlyreduced as compared to the reaction with a lighter oil, such as aneutral oil, which affords a larger percentage of insoluble reactionproducts. Ordinarily, if the reaction mixture contains insolubleproducts these materials can be removed by filtration or centrifugationperformed at an elevated temperature, usually about to 280 F. Othersuitable hydrocarbon oils which can be reacted with phosphorus sulfideinclude olefins such as cetene, melene, high molecular weight alkenesobtained by cracking petroleum oil, etc. and olefin polymers such asthose obtained from the liquid phase polymerization of butylene andisobutylene in the presence of a Friedel-Crafts type catalyst.

The phosphorus sulfide hydrocarbon reaction product is added to thelubricating base oil in small amounts usually about 0.5 to 5%,preferably about 1 to 3%. The weight ratio of the sulfurized fatty oilcomponent to the phosphorus sulfide hydrocarbon material can range fromabout 1 to 5: 1, preferably about 2 to 3:1.

The sulfurized fatty oil which forms the second component of theadditive combination is a natural or specially prepared ester ofunsaturated fatty oils having 12 to 20 carbon atoms in the fatty or acidradicals, sulfurized as with sulfur flowers, for example, at atemperature of about 350 F. for 6 hours to provide about 9 to 14% sulfurin the ultimate product. It is generally added to the lubricating oil inminor amounts, for instance about 2 to 10%, preferably about 3 to 5% byweight.

The lubricating oil base stock used in the present invention is oflubricating viscosity and can be, for instance, a solvent extracted orsolvent refined mineral oil obtained in accordance with conventionalmethods of solvent refining lubricating oils. Generally, lubricatingoils have viscosities from about 20 to 250 SUS at 210 F. The base oil ispresent in major amounts and may be derived from parafiinic, naphthenic,asphaltic or mixed base petroleum crudes and if desired, a blend ofsolvent-treated 3 Mid-Continent neutrals and Mid-Continent bright stocksmay be employed. A particularly suitable base oil used in thepreparation of the composition may be described as a lubricating mineraloil fraction having a viscosity index of about 100.

If desired other additives may be included in the lubricating oilcomposition of the present invention so long as they do not have anunduly adverse elfect upon the increased Timken load value provided bythe method of this invention. These additives can be, for example, otherextreme pressure agents, pour depressors, corrosion inhibitors,anti-foam agents etc.

The following examples are included to further illustrate the presentinvention.

Example I To a base oil consisting of 38% of a Mid-Continent lubricatingoil having a viscosity of about 46 SUS at 210 F. and 62% of aMid-Continent lubricating oil having a viscosity of about 150 SUS at 210F. was added 6.7% of an additive combination, designated A, having thefollowing composition:

Percent Phospho-sulfurized mineral oil bright stock (1.5%

S) 30 Sulfurized sperm oil (11% S) 67.5 Lauric acid 2.2 Trioxane 0.3

and the mixture was blended by heating up to 140 F. with stirring for 20minutes. Timken safe load tests on the blend ranged from 30 to 40pounds.

A portion of the blend was then heated at 200 F. for 40 hours and Timkensafe load values of the blend at various intervals during the heatingwere determined. Another portion of the blend was heated with stirringfor 1 hour at 250 F. The results of the tests are shown in Table Ibelow:

TABLE I Regular Timken Safe Load, Pounds Time, Hours Blend Blend BlendHeated at Heated at F 1 Blend prepared by heating base oil and additivesfor minutes at 140 The data show that heating a blend of a lubricatingbase oil and an additive combination containing a sulfurized sperm oiland phosphosulfurized mineral oil as extreme pressure agents at 200 F.up to 16 hours results, if anything in a decrease in load capacity.After 24 hours, however, a higher Timken load of 50-pounds is obtained,increasing to 65 pounds after 40 hours. The data also show that heatingthe blend at a higher temperature. i.e. 250 F for only an hour providesa Timken safe load value of 60 pounds. In comparison the essentiallyunheated blend exhibited a Timken load of to 40.

Example 11 In this example one portion of the additive combination A ofExample I was heated at 200 F. for hours and another portion at 250 F.for 16 hours. At periodic intervals during the heatings, samples of theheated additive combination were added to the base oil of Example I inan amount of 6.7% by weight and the Timken safe load value of theresulting blend was determined. The results are shown in Table II below:

TABLE II Regular Timken Safe Load, Pounds Time, Hours Additive AdditiveAdditive Package A Package A Package A Unheated 1 Heated at Heated at 1Blended with base oil by heating for 20 minutes at 140 F.

The data of Table II demonstrate that heating the sulfurized fattyoil-phosphorus sulfide hydrocarbon combination per se in accordance withthe method of the present invention, also provides an increased Timkensafe load value when the combination is added to the base oil. Theresults show further that heating the addit-ive combination itself at200 F. appears to effect a more rapid increase in Timken load value thanobtained when the oil blend is heated at the same temperature and thatan ultimately higher load value is obtained. Best results, are obtainedwhen the additive combination itself is heated at a temperature of about250 F. In this treatment a Timken safe load of pounds was obtained afteronly one hour, increasing to 70 pounds after two hours, and to more than80 pounds, with no failure, after eight hours.

It is claimed:

1. An additive combination which consists essentially of an oil-solublesulfurized unsaturated ester of a fatty acid having 12 to 20 carbonatoms in the fatty acid radical and an oil-soluble phosphorussulfide-hydrocarbon oil reaction product, heated at a temperature ofabout 200 to 350 F. and for a time sufiicient to increase its Timkenload value increasing characteristics, the weight ratio of saidsulfurized unsaturated ester to said phosphorus sulfide-hydrocarbon oilreaction product being about 1 to 5:1.

2. The additive combination of claim 1 wherein the sulfurized ester issulfurized sperm oil.

3. The additive combination of claim 2 wherein the phosphorus sulfidehydrocarbon reaction product is prepared by reacting about 7 to 17weight percent of phosphorus pentasulfide with a mineral oil brightstock at a temperature between about 400 to 500 F. for about 10 to 20hours.

4. A lubricating oil composition having an improved Timken breakdownload value consisting essentially of a mineral lubricating oil and smallamount sufiicient to increase the Timken breakdown load value of saidoil of the heated additive combination of claim 1.

5. The composition of claim 4 wherein the phosphorus sulfide-hydrocarbonoil reaction product is prepared by reacting about 7 to 17 weightpercent of phosphorus pentasulfide with a mineral oil bright stock at atemperature between about 400 to 500 F. for about 10 to 20 hours.

6. A lubricating oil composition having an improved Timken breakdownload value consisting essentially of a mineral lubricating oil and asmall amount sufiicient to increase the Timken breakdown load value ofsaid oil of an additive combination which consists essentially ofoil-soluble, sulfurized sperm oil and an oil-soluble phosphorussulfide-hydrocarbon oil reaction product, said combination having beenheated at a temperature of about 200 to 350 F. and for a time sufficientto improve its Timken load value increasing characteristics, the weightratio of said sulfurized sperm oil to said phosphorussulfide-hydrocarbon oil reaction product being about 1 to 5:1.

7. A process for producing a lubricating oil composition having animproved Timken breakdown load value which comprises heating at atemperature of about 200 to 350 F., a mineral base oil of lubricatingviscosity having added thereto a small effective amount of each of anoilsoluble sulfurized unsaturated ester of a fatty acid having 12 to 20carbon atoms in the fatty radical and an oilsoluble phosphorussulfide-hydrocarbon oil reaction product, the weight ratio of saidsulfurized ester to said sulfide-hydrocarbon oil reaction product beingabout 1 to 5:1, and the heating being conducted for a time sufficient toincrease the T imken breakdown load value of the lubricant by at least15 pounds.

8. The process of claim 7 wherein the sulfurized ester is sulfurizedsperm oil.

9. The process of claim 7 wherein the phosphorus sulfide-hydrocarbonreaction product is prepared by reacting about 7 to 17 weight percent ofphosphorus pentasulfide with a mineral oil bright stock at a temperatureof about 400 to 500 F. for a period of about 10 to 20 hours.

References Cited by the Examiner UNITED STATES PATENTS 2,640,030 5/1953Fischl et a1. 252-46.6

4/1943 K6180 et al. 25246.6

1. AN ADDITIVE COMBINATION WHICH CONSISTS ESSENTIALLY OF AN OIL-SOLUBLESULFURIZED UNSATURATED ESTER OF A FATTY ACID HAVING 12 TO 20 CARBONATOMS IN THE FATTY ACID RADICAL AND AN OIL-SOLUBLE PHOSPHORUSSULFIDE-HYDROCARBON OIL REACTION PRODUCT, HEATED AT A TEMPERATURE OFABOUT 200 TO 350*F. AND FOR A TIME SUFFICIENT TO INCREASE ITS TIMKENLOAD VALUE INCREASING CHARACTERISTICS, THE WEIGHT RATIO OF SAIDSULFURIZED UNSATURATED ESTER TO SAID PHOSPHORUS SULFIDE-HYDROCARBON OILREACTION PRODUCT BEING ABOUT 1 TO 5:1.
 4. A LUBRICATING OIL COMPOSITIONHAVING AN IMPROVED TIMKEN BREAKDOWN LOAD VALUE CONSISTING ESSENTIALLY OFA MINERAL LUBRICATING OIL AND SMALL AMOUNT SUFFICIENT TO INCREASE THETIMKEN BREAKDOWN LOAD VALUE OF SAID OIL OF THE HEATED ADDITIVECOMBINATION OF CLAIM 1.